Wobbler drive mechanisms



April 28, 1953 E. K.`sPARMANN woBBLER DRIVE: MECHANIsMs 3 Sheets-Sheet 1Filed June 8, 1949 FIG. 1A

FIG. 1

IIIIIIIII-llll lilllllllllll INVENTo ,EDMom ERNST KARL SPARMANN ATTORMYApril 28 1953 E. E. x. sPARMANN 2,636,392

woBBLER DRIVE MEcHANIsMs Filed June 8, 1949 3 Sheets-Sheet 2 FIG. 2 FIG.3

v INVENTOR. EDMQND ERNST KARL sPARMAm M46; f ATTORNEY April 2s, 195sFiled June 8, 1949 '5. E. K. SPARMANN woBBLER DRIVE MECHANIsMs '3sheets-sheet s INVENTOR.l EDMOND ERNST KARL SPARMANN ATTORNEY PatentedApr. 28, 1953 WOBBLER DRIVE IVIECHANISMSl Edmund Ernst Karl Sparmann,Stockholm, Sweden Application June 8, 1949, Serial No. 97,884 In SwedenJune 8, 1%4'8 13 Clainls.

The present invention relates to improvements in piston engines havingat least two pairs of pistons running in individual cylinders generallyarranged circumferentially around the engine shaft which is parallelwith the axis of the cylinders. The invention is of particular interestin such engines in which the cylinders in each pair have opposed Workingstrokes and are interconnected by piston rods coupled to a non--rotatable wobbler body which is rotatably but non-displaceably journaledon the engine shaft. Thanks to their compact design such engines permita considerable reduction of the external dimensions and constructionalweight for the same engine output as compared with piston engnes ofconventional designs. One of the most important of the several problemsappertaining to such motive power` engines or Working engines, such ascompressors, pumps etc., with wobbler drive, concerns the suitabledesign ci the mechanism for power and motion transmission between thereciprocating working pistons travelling in paths parallel with theengine shaft and the periphery of the wobbler plate. An object of thepresent invention is to give a practical solution of this particularproblem so that the inanifold and important advantages aimded by thelogical application of the wobbler plate principle, in addition to thosealready named, can be realised.

Due to the somewhat complicated three-dimensional. paths of movementresembling lemniscate motions described by a point situated on theperiphery of the Wobblerplate. the task is rendered particularlycoupling' between each piston and the wobbler plate must, on thisaccount, possess live deg-rees of' freedom, and at the same time beablev to hear the stresses iin-.- posed which in high speed. intern-alcombustion engines having high compression reach considerablemagnitudes. An additional and very important requirement must be met inthis respect, i, e. that movements oi the reciprocating masses; such aspistons, piston rods, etc., .rust be as equivalen-t or so-calledharmonic oscillations as possible, so that a complete dynamiccounterbalancing of the engine shall be attainable. Finally it isimperative for the complete realisa tion of several of the mostimportant advantages of the wobbler plate principle, that two. pistonscan at the same time-be attached. to: each attachment point on theperiphery oi thewobbler plate, namely one on each side of the so-calledwobbler plate-y plane..

While usingsimple constructiona-l elements already well tried in theart, the present invention has been developed with a View tobring abouta fully satisfactory .solution oi this important particular problem forwobbler plate engines from a theoretical and practical View point. Theinvention is substantially characterized in that said piston rods areinterconnected by a knee action unit bendable only in a rst planeincluding the commu axis of the pair of cylinders, said unit including acoupling element upon which said connecting rods are journalled s0 as tobe swingable only in said rst plane and to be displaceable withoutrotation in a second plane perpendicular thereto, said coupling elementbeing pivoted on said wobbler body so as to be rotatable in relationthereto about an axis extending in the wobbler plate plane.

The idea of the invention can be realised in a multitude of differentembodiments and some characteristic examples are diagrammaticallyillustrated by the accompanying drawings. All ci the parts not necessaryfor the illustration of the present invention have been omitted from thedrawings for sake of elearness.

Fig. 1 is a lateral view partly in section showing,J an example or'piston connecting. mechanism embodying the invention.

Fig. 1A is a fragmentary section similar to the left hand portion ofFig. 1 showing a diiiferent form. o'. the pis-ton connecting mechanism.

Fig. 2 shows a detail of the construction shown in Fig. LA, namely thecoupling together of the big-ends of the two piston rods to a kneeaction unit Elige. 3, 4. and 5 sho-w one of thev coupling elements ofthe mechanism used in Figs. 1, 6, 'Z and 8 three different projections,partly in section.

Figs, 6.r 7 and 8 show a wider variant oi. the ideay of the invention invarious projections, and in various positionsFig.. 6 at a dead centreposition and partly in axial section and Fiss. 7 and the same variantvof. the invention in a position lialiway'between the dead centres of thepistons,

Fig. l presenting a view at right angles to the engine sha-ft partly insection and Fig. 8 an axial section through the arrangement along theline d-tin Fig. 'il' Fis. 9- shows still another variant of the idea orthe invention. which is principally applicable to. a, construction ofthe: wobbler plate diiering from that shown. in Fig. 1.

Fig. i() isa diagrammatic view of the wobbler plate' bodyAv used. inFig. .9k it the same is seenr in the direction: of theV arrow A in Fig.9, i'. e. in the 3 direction of the tilted crank pin of the engineshaft.

Fig. 11 shows an analogous coupling element as shown in Figs. 3 to 5,but altered in construction to suit the variation according to Fig. 9.

In Fig. 1 the centre line of the engine shaft II is represented by I.The engine shaft I I differs from an ordinary crank: shaft in that it isprovided with a tilted crank pin 22 on which the so-called wobbler platebody is so journalled that it is rotatable on the crank pin 22 but notslidable on it in an axial direction. The centre line 2 of the tiltedcrank pin intersects the centre line I of the engine shaft at an angle aat a point O, which point is also called the wobbler plate centre orwobbler plate plane centre as the plane situated in the point O at rightangles to the tilted crank pin 22 or the centre line 2 thereof is calledthe wobbler plate plane.

When the engine shaft II is rotated the wobbler plate plane performs, asis well known, its characteristic wobbling motion. In order that thewobbler plate mechanism can function at all it is necessary to preventthe wobbler plate or the wobbler plate body 3 from participating in therotation of the engine shaft II by means of some suitable anchoringrarrangement. Such an arrangement has not been drawn in the figurespartly because it constitutes a separate problem and is therefore notthe object of this invention and partly to permit a clearer illustrationof the idea of the invention. Such anchoring means are described, forinstance in my copending applications Serial No. '715,265 filed December10, 1946, now Patent 2,550,613, and Serial No. 42,116 led August 2, 1948now Patent 2,550,612. It may, however, be mentioned, that as` is wellknown, the condition for the dynamic counterbalancing of the mass forcesof a wobbler plate engine is that all of the points situated in thewobbler plate plane and at a distance R from the wobbler plate centre Odescribe three-dimensional paths resembling lemniscate motions which arein all respects equal to one another and which are situated on aspherical surface with the radius R. The greatest length S of these loopcurves corresponding to the distance between the dead centres of themechanism or its length of stroke is the equal to 2.R.cos a and theirgreatest widths d in a tangential direction d=R.(l-cos a). In the middleof Fig. 1 such a movement path has been drawn in as a dash and dot lineL around the point O.

The wobbler plate body 3 has only been dlagrammatically indicated in thefigures and has therefore here, as an example, been given thefundamental form of a double truncated cone with a common base situatedin the wobbler plate plane. The wobbler plate body can, of course, beformed in another manner and is independent of the present invention.Some designers prefer, for instance, to give the wobbler plate body theform of a single cone which, in the centre of its base situated in thewobbler plate plane, is journaled on universal joints, and the engineshaft does not pass through the Wobblei` plate body but is coni-ined toa single crank arm in which the cone shaped point of the -wobbler platebody is rotatably journaled, and 4by means of its crank arm the engineshaft forces the cone shaped point of the wobbler plate body to move ina circular path. Furthermore a number of other constructional forms ofwobbler plate bodies of so-called wobbler plate rings are 4 known, whichcan also be utilized with the present invention.

The working cylinders of all wobbler plate engines are, as is wellknown, arranged around the engine shaft II approximately as cartridgesin a revolver drum. For the full realisation of the numerous principaladvantages of the woblbier plate system in the most suitable manner itis expedient to arrange the cylinders on both sides of the wobbler plateplane, so that two working cylinders always lie in coaxial alignmentwith each other. For the sake of clearness only four such cylinder'pairs, providing eight working cylinders have been assumed in Fig. 1,and of these only two have been diagrammatically indicated in the axialsection, namely 5 and 5I). Likewise, eight cylinders are assumed in thecase of the embodiment of Fig. 1A, two cylinders, 5 and 6G, being shown.Normally in practice however, a larger number of cylinders will bearranged, partly to achieve the maximum possible engine output with theminimum space and constructional weight, partly to obtain as even atorsional moment as possible.

In this construction example as many journal pins 4 as there are pairsof cylinders are secured to the wobbler plate body to extend in radialdirection from its periphery. On each of these pins 4, a couplingelement 40 is so mounted that its longitudinal axis is always at rightangles to the centre line cf the corresponding pin 4, and that it isonly rotatable around but not displaceable along the last named line.The pin 4 and the element 4Qfthus constitute a kind of Cardan joint.

The fundamental form of the element 40 is illustrated by the Figs. 3, 4and 5 in three different projections, and partly in section. As theFigs. 3, 4 and 5 show, the element 40, which is cylindrical on theoutside, is provided with a hole 4I in a direction at right angles tothe axis of the element 48. This hole 4| serves as a rotatable bearingfor the element 43 on the pin 4. Displacement along pin 4 is preventedby the end surface 43 of the pin restingagainst a wall 44 at the bottomof the hole 4I, while, for example, a nut 45 is threaded on an extensionbolt projecting from the pin 4 and retains element 4B on pin 4. Y

The big-end of piston rod 5I is mounted not only rotatably but at thesame time axially slidably on the element 4G, i. e. laterally slidablerelative to the center of the Cardan joint formed by the pinrli 'and theelementllil.

This` possibility of lateral sliding of the piston rod along the one ofthe elements 4Q secures for this Cardan joint three degrees of freedom,which is one of the characteristics of the invention rela#- tive to theknown art. This lateral slideability in thecoupling of the piston rodsto the wobbler plate permits a radius in the wobbler plate plane throughthe centre of the coupling element i. e. the center of the pin 4 and theelement 4U to freely describe the apparent oscillating movements aroundthe centre line of the engine shaft, which are characteristic for thetheoretically correct motion of the wobbler plate. The small end of thepiston rod 5I is in a manner known per se rotatably journaled on agudgeon lpin 54 inthe piston 52. v

According to the construction illustrated in Fig. l the second piston 55of the piston pair is attached by means of a so-called articulatedconnecting rod 53 which is in a known manner rotatably journalled bothrelative to the piston 55 by means ci' the gudgeon pin 5c and relative:to the main piston rod :t by means. of bearingbolt, 153 carried by thebearing; brackets 55 on the big-end of the main piston rod. The bearingbolt 5;'5 is arev ranged parallel to the axis of but laterallyoffset inrelation to. the elementv all: so that the two. con meeting rodsll and53 of the piston lea-ir 52;, 55 constitute a knee action unit which, onthe other hand', is rigid'lin a direction at right: angles to the planeyof bending, i. e. rigid in a direction tan gential to. the Wobblerplate. This. is indicated i11- ter alla, by the piston pai-r drawn inthe centre of Fig. l andgby the design or' the `piston rods 5i! and 53.The big-end of the. main piston rod' A5I provided with openings Sil:which allow suilcient freedom of movement between the pin :t and itsextension bolt, if any. on the. one side and the piston. rod 5l, on the.other side, rotatably and slidealoly mounted on the element to.

A Variant` construction is. shown in Fie. la differs trom the one; rstdescribed, appearing on. the left. hand.- side of Fig; l in that the.piston rod. 63 or the' lower piston S5 isx in a. manner known per seformed as. a forked piston4 rod which is rotatably iournaled on andencompasses the outside of the big-vend of 'the piston rod, Si... In,this way the axis of; rotation of` the Piston rodi $3 'coincides withthe axis ci rotation of' the piston rod 6l both axes. passing throughthe center point perneldicularly to the plane, of

Fis. 1

Fig., a shows the ioining together of the bigendsoi the two piston rodsv6l; and. G3i partlyin the left halt of the. sure in a section on theyline I-- in. Fig... LA. partly'. in the right half' ci the. Fig. 2.,. aviewer the saure detail ii it is; seenv in a, direction atv iight.angles to the .engine sliait Il. The element, 4o can. eten in thisvariant. be suitably termed in the. same, manner as shown by FissA 3, 4and o.

Figs. 6, 7 anjd 8 show an additional variant of the idea of; theinvention. Fig. 6. a, View of a pair of pistons'in a. direction.tangential to the wobbler plate, where the, mechanism is shown, in anaxial section. through the. nin 4.., Fics. '2 and 8. show the samearrangement when the pistons are in, a position between. the deadcentres and seen from twodiierent directions at right angles to oneanother... The piston l2Y has been drawn as a sectionthroosh the.audgeon pin and the cylinder axis ,in order to illustrate an expedientdetail construction for theY attachment .of .the piston to the. smallend or the. piston rod. Fiera an axial section through the mechanism,show# ing the upper piston rod on the. section .line 84H8 in Fig. 1' anda. side. view-zot the lower piston rod 13.

As is made evident by theI three last. named iig--` ures the two. pistonrods?! and 13 are identical and rotatably connected to a link memberhavingra central, bearing sleeve 80 byV means oi crank pins i8 and 1Sharing parallel axes which are later allyy offset on both sides of andperpendicular to the axis of the. pin- 4.. This central bearing sleeve.80 is not rotatably mountedon the element. 40 and is only longitudinallyslidable therevon, i. e. according to the-idea of' the invention, in adirection at right angles to the pin 4. This axial siideablt'y of thebearing sleeve B0 without rotation relative to the pin 4D is assured,for example in FgQ, in that the outer-opening 59 in the bearing sleeve8l! is oval andthe width ,of

the oval is equivalent to the outer diameter-"of a bearing ring 48 whichis rotatably journaled on a. hearingL blush 41 which. last named slid ontoy an extension or the pin 4 and held on the same. by .means of avthreaded nut. "4'5.. In this way the element, 40 is yat the. same time.located on the pin 4 in the axial direction duc to. the bearing bush41.' restingzin the bottom of the hole 4I in the. element 40., and thewall 44 in its turn ind's support. against the end surface of thel pin 4see also `Figs. 3 to 5.). The nut 45 only tightened so much that theWall 4'4 and the end surface -43 of .the pin 4 can function as an axialbearing. The length of the oval outer opening 53 in the central bearingsleeve 80 lies in the axial direction of said sleeve and must be atleast equal to the sum of the diameter of 'the bearing ring plus theWidth d of the lem-niscate shapedmovementl path L V(see Fig. 1)Which'the cen-trepoint. describes during an engine revolution.

Fig-si '7 and 8 also illustrate a means foi-"preventing the pistons frombinding in the 'cylinders if their vlongitudinal axes should notcoincide accurately, or the rotary axes of al1- y'of the piston rods inthe knee action unitshould not lie exactly parallel to one another or tovthe axis of the bearing sleeve SS. The means consists therein that thesmall ends of the piston rod-s are connected to the piston by vmeans ofuniversal joints, for example as suggested in Figs. 7 and 8. Instead ofthe cylindrical holeat the small ends of the piston rods, a ball race isarranged in which a rin-g el spherical on its outside is fitted. Theball race in the small end of the piston rod is provided on its one sidewith cylindrical milled out recesses which are as wide as the ring 8i isthick. The ring 8l can therefore be slid into the ball race from that`side and their be rotated The piston rod can be lat erally located onthe gudgeonup'in 'M by inserting distance rings 32 between the flatfaces of the spherical ring and the inner wall ofthe piston. y

It may here be interjected that unnecessary lateral playr between thepistons and their piss ton rods should be avoided in all theconstructional forms, partly to avoid disturbing scccndary noise duringthe running of the engine, partly to provide against unsymrnetrical andaclverse loads on the knee action unit slideably mounted on element 4B.Purely theoretically it is true that itshould be possible to assign theWhole of the lateral slideability of the knee aeticn unit to thegudg'eon pins, but this Should in practice be accompanied byconsiderable draw* backs because the load on the gudgeon pins iscontinually fiuctuatingand is, at the same inf starrt, very different onthe two gudgeon pins of two cooperating piston-s. lAs a result, even thefriction between the small ends ct thefpistcn rods and their respectivegudgeon-pins is unsymmetrical in comparison with the connectingmechanism and this should occasion adverse` wor-king conditions for thevarious bearing surfaces of the Whole piston connecting mechanism.

It is true that the lateral pressure ofthe pistons against the cylinder'walls will, in thel case of' the constructions accor-ding' to Figs. 6, 7and 8, be somewhat greater than in the ease of the other Variationsshown in the drawings,l but it amounts nevertheless at .its maximum atthe intermediate position ci" the pistons between their dead centresonly to about half the values reached in ordinary crankshaft engines. Anad'- vantage of this construction compared Withvthe other constructionsis, on the other hand, that the stroke of the pistons and hence thecylin der capacity is about greater for the same angle a of inclinationof the tilted crank pin and for the same distance between the cylindersand the engine shaft.

Fig. 9 shows a further construction which is particularly suitable ifthe designer wants to form the whole wobbler plate body of light metal.The pins 4 are not here, as in the earlier examples, arranged in aradial but in a tangential or peripheral direction to the wobbler plateand with their centre lines in the wobbler plate plane. The element 4I)is rotatable around pin 4 but not slidable on same as this is preventedby the fitted distance tubes 41. In other respects the constructioncompares most closely with that illustrated in Fig. l with the exceptionof that, in this variant, the hole M in the elementy passes righttherethrough, which is apparent from Fig. 1l. The bolts in the kneeaction unit are, of course, again parallel to one another but are atright angles to the pin 4. The knee action unit is here axially slidablealong the element 40, that is, in a radial direction relative to thewobbler plate body, i. e. in a direction at right angles to the pin 4.

Fig. l0 shows a portion of the wobbler plate body used in Fig. 9 andseen in the direction of the tilted crank pin and of the arrow A in Fig.9. Here, as previously, only four pairs of cylinders have been assumedfor the sake of clearness of .j

the gures although, as mentioned, in practice it is more advantageoustogroup a larger number of cylinder pairs around each wobbler plate.

It is true that the piston attachment mechanism according to the presentinvention is, from the kinematic pint of view, not absolutely correct,but as the deviation from the absolute correct values is, even in themost adverse case, less than 0.25%, this circumstance has no practicalimportance whatever.

However, the many practical advantages which the present inventionaffords in comparison with the numerous hitherto known designs are ofall the more positive value. Of these may be named, for instance, thatthe lateral pressure of the pistons against the cylinder walls isreduced to a minimum, that the piston rods are not subjected to bendingloads or fatigue risks, that all the vital parts can be constructed anddimensioned in accordance with the requirements and experience regardingstrength and service reliability and especially for high compression andhigh speed internal combustion' engines. If the design is applied totwo-stroke engines. being particularly suitable. the resulting loads onthe connecting joints, the wobbler plate body, the engine shaft and onall of the bearing surfaces will always only amount to the differencebetween the Working pressure on one piston reduced by the mass forces ofthe two pistons and of the knee action unit of the piston rods. Thedesign is composed of only simple elements well proved in practice, isinexpensive to manufacture and assemble, permits ample dimensioning ofall bearing surfaces and material cross-sections, and obviates the riskof the pistons or other parts binding or seizing on account of runningloads or deformation at various conditions of heat. vThe reciprocatingpiston movement is combined with a simultaneous slight rotary movementaround the cylinder axis since the apparent oscillations of the wobblerplate body around the engine shaft are transmitted to the pistonsthrough the connecting mechanism. This prevents scores arising in thewearing surfaces of the piston and the cylinder, distributes thelubricating oil film more evenly, etc. The same favorable type ofmovement, i. e. a combination of rotary and reciprocating movement,occurs in the constructions according to Figs. 1 and 9 between theelement 40 and the big-ends of the main piston rods '5l and =6I.

The idea of the invention permits, of course, further variations andcombinations, and is applicable to other constructions of wobbler platesor wobbler plate mechanisms, and to motive power engines as well asworkingv engines, such as compressors, pumps, etc. which make use of thewobbler plate principle.

I claim:

1. In Ia piston engine of the wobbler type, the combination, with a.main shaft, a rigid nonrotatable wobbler body non-displaceablyjournaled thereon, at least two pairs of cylinders having their axesparallel with the axis of rotation of said shaft and with the cylindersof each pair located on opposite sides of said wobbler body respectivelyand coaxial with each other, pistons reciprocable on opposed Workingstrokes in each pair of cylinders `and means comprising articulatedpiston rods connecting each pair of pistons, of a knee action couplingunit for connecting the piston rods of each pair of pistons to saidwobbler body, each of said units being bendable only in a first planeincluding the common axis of the pair of cylinders and comprising acoupling element turnably mounted on said wobbler body at a fixed radiusfrom the center thereof to turn relative to the wobbler body about anaxis extending inthe plane of the wobbler body, and the piston rods ofthe pair connected' to said coupling element being connected so as toturn only in said rst plane and to slide relatively to said element in adirection perpendicular to said rst plane.

2. An engine as defined in claim l, -in which said iirst plane extendsradially from the axis of rotation of said main shaft.

3. An engine as dened in claim 2, in which said axis about which saidcoupling element turns extends radially .in the plane of the wobblerbody from the center thereof.

4. An engine as dened in claim 1, in which said iiist plane extendsperipherally with respect to said wobbler body.

5. An engine .as dened in claim 4, in which said axis about which saidcoupling element turns extends in a peripheral direction in the plane ofthe wobbler body.

' 6. An engine as defined in claim 1, in which said coupling element isconnected to the wobbler body by a pivot connection preventingdisplacenient of the coupling element relative to the wobbler body.

i '7. An engine as defined in claim 1, in which a first piston rod -ineach pair is mounted to have both turning and displacement movementrelative to the coupling element and the second piston rod of the pairis non-displaceably pivoted on said first piston rod. to turn in saidfirst plane.

8. An engine as defined in claim 7, in which said second piston rod isturnable about an axis coinciding with the axis about which said rstpiston rod turns.

9. An engine as defined in claim 8, in which said piston rods-areprovided with sleeve-shaped end portions, the sleeve-shaped portion ofsaid first piston rod encircling said coupling element and thesleeve-shaped por-tion of said second pis- 9 ton rod being coaxial with`and encircling the sleeve-shaped portion of said first piston rod.

10. An engine as dened in claim 7, in which said second piston rod ismounted to turn about an axis parallel with and laterally oiset from theaxis `about which said rst piston rod is turnable.

1l. An engine as deiined in claim l, in which the coupling unit includesa link member axially displaceably and non-rotatably mounted on saidcoupling element, the piston rods of the associated pair beingindividually connected to said link member to be non-displaceable withrespect thereto and turnable about axes each oiset with respect to andperpendicular to the axis about which said coupling element is turnablewith respect to said wobbler body.

l2. An engine as dened in claim 1, in which a universal joint connectionis provided between each of said piston rods and the piston to which itis connected.

13. In a piston engine of the Wobbler type, the combination, with a mainshaft, a rigid nonrotatable Wobbler body non-displaceably journaledthereon, yat least two pairs of cylinders having their axes parallelwith the axis of rotation of said shaft and with the cylinders of eachpair located on opposite sides of said wobbler body respectively andcoaxial with each other.

10 pistons reciprocable on opposed Working strokes in each pair ofcylinders and means comprising articulated piston rods connecting eachpair of pistons, of a motion transmitting unit connecting the pistonrods of each pair to said Wobbler body, each such unit comprising acoupling element, means including said element providing a Cardan typejoint between said Wobbler body and said pair of rods, said elementbeing turnably mounted on said wobbler body at a xed radius from thecenter thereof land providing a journal and the connection between saidrods and said element providing for both turning movement of the rodsrelative to the axis of the journal and movement of the rods axiallywith respect to the journal.

EDMUND ERNST KARL SPARMANN.

References Cited n the le of this patent UNITED STATES PATENTS NumberName Date 1,787,493 Redrup Jan. 6, 1931 1,814,946 McGeorge July 14, 19312,247,527 Stinnes July 1, 1941 FOREIGN PATENTS Number Country Date212,884 Great Britain May 18, 1925

